Masters Theses

Date of Award

8-1981

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant, Soil and Environmental Sciences

Major Professor

V. H. Reich

Committee Members

F. L. Allen, D. R. West

Abstract

A field study was conducted to evaluate the effects of awn removal on yield and yield components in three soft red winter wheat varieties (Triticum aestivum L. em Thell). The three varieties used were Arthur, a tip awned type, 576, and Hart, both fully awned types. Five awn removal treatments, at heading, 1, 2, 3, and 4 weeks after heading (C-0, C-1, C-2, C-3, and C-4, respectively) and a control (C) were used to determine the role that awns contribute to yield in these varieties. There were significant differences in yield per sample due to awn removal treatments. Awn removal 2 weeks after heading (C-2) gave the highest yield per sample of 70.77 g. This treatment resulted in significantly higher (P < .05) yields than all other treatments except the control (C) which yielded 64.26 g per sample. The C-2 treatment was also significantly higher (P < .05) than the other treatments in yield per spike except C-4 and C. C-2 had a significantly higher (P S .05) number of spikes per sample (74.8) than C-0. The number of kernels per spike was significantly higher (P < .05) for C-2 than for C-0 and C-3. Removal of the awns had an affect on hundred kernel weight. C-1 (3.17 g) was significantly lower (P < .05) than C and all other treatments except C-3 (3.28 g). C-4 had a significantly lower (P < .05) test weight than C-0, C-2, and C, 77.4 versus 78.0, 78.4, and 78.3 kg/hl. There was significant variety X clipping interaction in yield per sample, yield per spike, and hundred kernel weight. In yield per sample and yield per spike the interaction was due to significant variation among the varieties in C-0 and the lack of variety differences in the other treatments. In hundred kernel weight Hart and Arthur reacted much the same to the awn removal treatments, but S76 varied from the response patterns of these two varieties. Significant variation in yield per sample due to treatment effects did not occur in the tip awned variety Arthur. However, there were significant differences among the treatments for yield per spike in Arthur. The awn removal treatments had a significant affect on yield per sample in the fully awned variety 376. However, two factors which possibly biased the C-2 effect were the substantial rainfall (> .50 cm) and the high number of spikes per sample in 576. Significant differences in yield per sample, yield per spike, and hundred kernel weight due to the treatments occurred in Hart, another fully awned variety. The earlier the awn was removed in Hart, the greater the reduction in yield. The one exception to this statement was the C-2 treatment. The rainfall mentioned above was believed to have increased the yields in all three varieties.

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